One of important factors that should be considered during four-dimensional radiation therapy or respiratory-gated radiation therapy for a patient is an assumption that the patient's organs move in constant patterns during the radiation therapy. There may be various kinds of movement factors that have an influence on movement of organs of a human. Among these, keeping respiration nearly constant is very important to radiation therapy.
In radiation therapy using medical radiation therapy equipment, it is most important to intensively irradiate tumor cells while minimize radiation dose to surrounding normal tissues. In particular, radiation therapy for a moving organ essentially requires a technique for controlling beams according to variation of geometric movement of tumor that occurs during the radiation therapy.
Several apparatuses are used to achieve prerequisites associated with respiration during the radiation therapy described above. However, since most of the apparatuses use only guiding signals, patients only intuitively breathe as they have practiced without checking their own respiratory status.
To this end, a conventional radiation therapy technique mainly uses a gating method in which a medical radiation machine is controlled to perform therapy using a real-time position management (RPM) system. However, success or failure of the therapy technique depends on stability of the patient's respiration, and also respiratory-gated radiation therapy for a patient having unstable respiration requires a long treatment time. In addition, since the RPM system sets a respiration phase using only a respiration period and applies the respiration phase to the respiratory-gated radiation therapy without considering a respiration pattern or a respiration volume, the RPM system has very low therapeutic accuracy.
In particular, stereotactic body radiation therapy for a moving organ may have a significantly long treatment time and a very high risk of side effects in comparison to conventional radiation therapies. Accordingly, in order to solve this problem, it is also important to educate and to train so that the patient has a stable respiration period and respiration volume.
Also, for radiation therapy patients having diseases associated with their lungs, it is actually very difficult to maintain stable respiration periods and respiration volumes. Accordingly, when respiratory-gated radiation therapy is conducted for patients with lung diseases, radiation should be delivered only when a respiratory status is stable, thus a breathing assistance device is definitely required
The aforementioned background is technical information which the inventors have had or obtained in the course of the present invention and thus may not be publicly known before the filing of this application.